Field of the Invention
The present invention relates to an image pickup apparatus provided with an image pickup element including a focus detection pixel.
Description of the Related Art
Japanese Patent Laid-open No. 2000-156823 discloses an image pickup apparatus that performs a focus detection by a phase difference method with focus detection pixels disposed at predetermined intervals among image pickup pixels. With the configuration of Japanese Patent Laid-open No. 2000-156823, image information partly lacks at the positions of the focus detection pixels. Thus, an interpolation calculation is performed based on information of image pickup pixels around each focus detection pixel so as to generate to an image signal. Sparsely arranged focus detection pixels can reduce image degradation due to pixel defects. However, those pixels degrade sampling characteristics of a focus detection image and thus degrade focus detection performance.
Japanese Patent Laid-open No. 2007-279312 discloses an image pickup apparatus capable of performing a highly accurate focus detection and a large defocus amount detection by performing the highly accurate focus detection by using a group of first focus detection pixels having a short image detection pitch and a large defocus amount detection by using a group of second focus detection pixels having a long image detection pitch.
However, in the configuration disclosed in Japanese Patent Laid-open No. 2007-279312, the first focus detection pixels are densely arranged to highly accurately detect a nearly-focused state. A pixel signal of each focus detection pixel is generated through interpolation processing using output signals of neighboring image pickup pixels and output signals of neighboring focus detection pixels. This configuration improves sampling characteristics of the pixel signal from the focus detection pixel but potentially causes partial image degradation in a focus detection region.